TypeError: argument of type 'NoneType' is not iterable

[OzEDev]

Exception in thread Thread-7:
Traceback (most recent call last):
File "/usr/lib/python3.4/threading.py", line 920, in _bootstrap_inner
self.run()
File "/home/simon/Bureau/code/web/firefox os/tidu contre tizef/git/tidutyzef/serveur/pyWebSocket.py", line 119, in run
self.__onreceive(data)
File "/home/simon/Bureau/code/web/firefox os/tidu contre tizef/git/tidutyzef/serveur/pyWebSocket.py", line 188, in __onreceive
self.onReceive(decoded)
File "/home/simon/Bureau/code/web/firefox os/tidu contre tizef/git/tidutyzef/serveur/Player.py", line 25, in onReceive
if not self.username and not "username" in data:
TypeError: argument of type 'NoneType' is not iterable

[OzEDev]

quand on ferme l'onglet qui charge